Latex, 235 thin film

Van Tent [ 12] reported a series of experiments in which he monitored the turbidity (UV-visible transmission) of latex dispersions and weight loss simultaneously. These experiments are examined here in some detail. Van Tail s latex samples had a veiy narrow size distribution and were stabilized (at 48 wt% solids) by the presence of 1 wt% sodium dodecylbenzene sulfonate, based iqum latex. Thin films (e.g. 30-40 pm) of dispersion were placed on a horizontal glass disc. The disk was mounted on the pan of a balance, and the interrogafing beam monitored a spot 0.3 mm in diameter in the centre of the disc. Because the temperature in the room could be controlled, the authors were able to compare the drying process for the same dispersion at tenqiaatures below, near and above the MFT. 

There are many temporary protectives on the market and it would be impracticable to describe them individually. However, they may be classified according to the type of film formed, i.e. soft film, hard film and oil film the soft film may be further sub-divided into solvent-deposited thin film, hot-dip thick film, smearing and slushing types. All these types are removable with common petroleum solvents. There are also strippable types based on plastics (deposited by hot dipping or from solvents) or rubber latex (deposited from emulsions) these do not adhere to the metal surfaces and are removed by peeling. In addition there are volatile corrosion inhibitors (V.C.I.) consisting of substances, the vapour from which inhibits corrosion of ferrous metals. 

Another largely unexplored area is the change of dynamics due to the influence of the surface. The dynamic behavior of a latex suspension as a model system for Brownian particles is determined by photon correlation spectroscopy in evanescent wave geometry [130] and reported to differ strongly from the bulk. Little information is available on surface motion and relaxation phenomena of polymers [10, 131]. The softening at the surface of polymer thin films is measured by a mechanical nano-indentation technique [132], where the applied force and the path during the penetration of a thin needle into the surface is carefully determined. Thus the structure, conformation and dynamics of polymer molecules at the free surface is still very much unexplored and only few specific examples have been reported in the literature. 

Over the last few decades, the use of radiation sources for industrial applications has been widespread. The areas of radiation applications are as follows (i) Wires and cables (ii) heat shrinkable tubes and films (iii) polymeric foam (iv) coating on wooden panels (v) coating on thin film-video/audio tapes (vi) printing and lithography (vii) degradation of polymers (viii) irradiation of diamonds (ix) vulcanization of mbber and rubber latex (x) grain irradiation. 

Electrostatics, effect on weighing, 26 243 Electrostatic self-assembly (ESA), of thin-films, 1 724-725 Electrostatic separators, 16 642 Electrostatic separation, 16 642-644 Electrostatic spray coating, 7 56-58, 74-75 Electrostatic stabilization, 10 119-121 of latex, 14 708-709 Electrosteric stabilization, 10 122 Electrostream (capillary drilling), 9 600 Electrostrictive coefficient tensor, 11 93 Electrostrictive devices, applications of, 11 103-104... 

Often the production of new materials such as composite materials heavily involves processes at interfaces. Thin films on surfaces are often dominated by surface effects. Examples are latex-films, coatings, and paints. The flow behavior of powders and granular media is determined by surface forces. In tribology, wear is reduced by lubrication which again is a surface phenomenon. 

The latex was cleaned by ion exchange and serum replacement, which gave the cleaned latex plus six serum fractions. The cleaned latex and the serum samples were analyzed by conductometric titration. Also, the amount of anionic emulsifier in the serum was determined by Fyamine 1622 colorimetric titration and thin-film chromatography, and the amount of nonionic emulsifier by iodine-iodide colorimetric titration and thin-film chromatography. 

Fig. 13. NSOM fluorescence (left) and force (right) images of 50 nm fluorescent latex spheres in a thin film. The fluorescence image exhibits high resolution while the small spring constant of the probe allowed the force image to be taken in contact mode without damaging the NSOM aperture.

Raw lacquer is called urushi. For our knowledge of the composition of urushi and the complex hardening process of the thin film layers, we now rely primarily on the recent work of Kumanotani and his coworkers (1-7). The sap of the Japanese lacquer tree is a latex containing 20-25% water, 65-70% urushic acid (urushiol), approximately 10% gummy sub-... 

In the context of polymers in industrial applications a number of key issues can be identified that are amenable to direct investigation and analysis by AFM approaches. From the preceding chapters the potential of probe microscopic techniques to conveniently visualize for instance surface (or bulk) morphologies and filler distributions has become obvious. Different classes of polymer materials, such as for instance thermoplastics, latexes, porous materials for membranes or thin films are subjected to different types of processing and treatments. The impact of all these modifications and the dependence on the process parameters can hence be closely monitored and in many cases quantitatively characterized by AFM. 

A different version of the adhesion method was used in [690]. An amidine-grafted polystyrene latex with IEP at pH 6 (electrophoresis) was used. lEPs of thin films of iridium and tungsten oxides (among other materials) were determined, and the results complied with standard methods. 

The role of surface viscosity and elasticity on the motion of a solid particle trapped in a thin film, at an interface, or at a membrane of a spherical vesicle has been recently investigated in References 604 and 605. The theoretical results ° have been applied to process the experimental data for the drag coefficient of polystyrene latex particles moving throughout the membrane of a giant lipid vesicle. Thus, the interfacial viscosity of membranes has been determined. 

Polymers with pendant cyclic carbonate functionality were synthesized via the free radical copolymerization of vinyl ethylene carbonate (4-ethenyl-l,3-dioxolane-2-one, VEC) with other imsaturated monomers. Both solution and emulsion free radical processes were used. In solution copolymerizations, it was found that VEC copolymerizes completely with vinyl ester monomers over a wide compositional range. Conversions of monomer to polymer are quantitative with complete incorporation of VEC into the copolymers. Cyclic carbonate functional latex polymers were prepared by the emulsion copolymerization of VEC with vinyl acetate and butyl acrylate. VEC incorporation was quantitative and did not affect the stability of the latex. When copolymerized with acrylic monomers, however, VEC is not completely incorporated into the copolymer. Sufficient levels can be incorporated to provide adequate cyclic carbonate functionality for subsequent reaction and crosslinking. The unincorporated VEC can be removed using a thin film evaporator. The Tg of VEC copolymers can be modeled over the compositional range studied using either linear or Fox models with extrapolated values of the Tg of VEC homopolymer. 

Polymers. The purpose of adding polymers to the concrete matrix is to improve the characteristics of the fresh concrete (such as workability) and also to enhance the hardened properties such as flexural strength, modulus of elasticity and adhesive performance [8]. The incorporation of polymers into concrete may be in the form of polymer modified concrete (PMC), polymer impregnated concrete (PIC) or as polymer concrete (PC) [9], For this project, the objective was to develop an ultra-lightweight concrete material using Portland cement as the main binder modified with a suitable polymer - thus a PMC application. The polymer modifiers selected for the development of the ultra-lightweight thin filmed material were a commercially available SBR latex as well as a readily available acrylic polymer. 

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